DNA helps trace early tundra-dwellers
Archaeological evidence clearly shows that a variety of cultures survived the harsh climate in Alaska, Canada and Greenland for thousands of years. But where did they come from? Did they come in several waves? When did they arrive?
Some answers are found in a comprehensive DNA study of current and former inhabitants of Greenland, Arctic Canada, Alaska, the Aleutian Islands and Siberia, conducted by an international team headed by the Centre for GeoGenetics at the Natural History Museum of Denmark. The results have just been published in the journal Science.
The researchers showed that the Paleo-Eskimo, who lived in the Arctic from about 5,000 years ago until about 700 years ago, represented a distinct wave of migration, separate from both Native Americans – who crossed the Bering Strait much earlier – and the Inuit, who came from Siberia to the Arctic several thousand years later.
Also, the genetic studies show that the Paleo-Eskimos were the first people in the Arctic, and they survived without outside contact for over 4,000 years, said Eske Willerslev who headed the project. The study also shows that the Paleo-Eskimos, after surviving in near-isolation in the harsh Arctic environment for more than 4,000 years, disappeared around 700 years ago – about the same time the ancestors of modern-day Inuit spread eastward from Alaska. ku.dk
‘In body’ potential for muscle regeneration
What if repairing large segments of damaged muscle tissue was as simple as mobilizing the body’s stem cells to the site of the injury? New research in mice and rats, conducted at Wake Forest Baptist Medical Center’s Institute for Regenerative Medicine, suggests that “in body” regeneration of muscle tissue might be possible by harnessing the body’s natural healing powers.
Reporting online in the journal Acta Biomaterialia, the research team demonstrated the ability to recruit stem cells that can form muscle tissue to a small piece of biomaterial, or scaffold that had been implanted in the animals’ leg muscle. The secret to success was using proteins involved in cell communication and muscle formation to mobilize the cells.
“Working to leverage the body’s own regenerative properties, we designed a muscle-specific scaffolding system that can actively participate in functional tissue regeneration,” said Sang Jin Lee, assistant professor of regenerative medicine and senior author. “This is a proof-of-concept study that we hope can one day be applied to human patients.” wakehealth.edu
Valuable materials remain in cellphone waste
Customers will buy more than 1.8 billion new cellphones by the end of this year only to abandon almost half of them to drawers, and they’ll recycle a mere 3 percent of them. But creative and enterprising efforts are underway to reverse the seemingly unstoppable tide, according to an article in Chemical & Engineering News, the weekly news magazine of the American Chemical Society.
Alex Scott, a senior editor at C&EN, notes that there is much to be recovered and re-used from a cellphone. An average mobile contains about 300 milligrams of silver and 30 mg of gold: Added up across all phones to be sold this year, the two metals alone are worth more than $2.5 billion. Cellphones are made with a few dozen additional elements, but the most high-tech recycling technology today can only recover about 17 of them at a maximum yield of 95 percent.
One idea dominating efforts to stem e-waste involves improving upon the modular phone idea, which allows users to replace parts but keep the main body of a phone intact. That way, some people could avoid buying whole new phones when they want to upgrade. Another major piece of a more sustainable mobile culture is the recycling process itself. acs.org